Organic semiconductor laser

ABSTRACT

An optically-pumped laser having a small-molecule thin organic film of DCM doped Alq 3 . Carrier transport properties of the small-molecule organic materials, combined with a low lasing threshold provide a new generation of diode lasers employing organic thin films. An electrically-pumped variant is also described.

GOVERNMENT RIGHTS

This invention was made with Government support under Contract No.F49620-96-1-0277 awared by AFOSR. The government has certain rights inthis invention.

RELATED APPLICATIONS

All or part of the present application claims the benefit, under 35U.S.C. § 119 (e)(2), of U.S. provisional application Ser. No. 60/046,061filed on May 9, 1997 and entitled ORGANIC SEMICONDUCTOR LASER.

FIELD OF THE INVENTION

The present invention relates to the field of light emitting devices, inparticular, to organic semiconductor lasers.

BACKGROUND INFORMATION

Several recent publications have reported either superluminescence oramplified spontaneous emission in polymeric organic light emitters suchas conjugated polymers. (N. Tessier et al., Nature 382, 695 (1996); F.Hide et al., Science 273, 1833 (1996)). The materials used in thoseemitters were spin-coated from a solution of the polymer or its chemicalprecursors. Optically pumped, stimulated emission from organic laserdyes, introduced into inert, spin-coated polymers or gels has beendescribed in the literature. (R. E. Hermes, et al., Appl. Phys. Lett.63, 877 (1993); M. N. Weiss et al., Appl. Phys. Lett. 69, 3653 (1996);H. Kogelnik et al., Appl. Phys. Lett. 18, 152 (1971); M. Canva et al.,Appl. Opt., 34, 428 (1995)).

Recent work has demonstrated gain-narrowed photoluminescence spectrawith full widths at half maxima (FWHM) of 40-60 Å in response to a shortpulse laser excitation, typically 1 μJ in a 10 ns pulse. (MaterialsResearch Society 1997 Spring Meeting, Abstracts H1.1, H1.6, H2.1, H2.2,H2.3.) Such work is potentially applicable to electrically pumpedorganic solid state lasers ("plastic lasers"). If realized, such devicescould offer low cost and ease of integration of laser sources ontoeither conventional semiconductor circuitry or lightweight plasticsubstrates.

Spun-on polymeric materials, however, do not exhibit particularly goodthickness uniformity, ability to achieve extremely high materialspurity, and ease of integration with other conventional semiconductorfabrication processes.

In the field of organic light emitting devices (OLEDs) for flat paneldisplay applications, small molecule OLEDs currently offer betteroperating lifetimes by an order of magnitude over their spin-coated,polymeric analogs. (L. J. Rothberg et al., "Status of and Prospects forOrganic Electroluminescence",J. Mater. Res. 1996, 11:3174; N. C.Greenham et al., "Semiconductor Physics of Conjugated Polymers", SolidState Physics 1995, 49:1.)

However, there has been no known demonstration of laser action in avacuum-deposited organic thin film structure. Furthermore, there isconsiderable skepticism about the realization of small-molecule organiclasers because of quenching processes which can occur in such materials.Such quenching processes are observed at high carrier densities and leadto decreased photoluminescence quantum efficiency. For example,bimolecular reactions in Alq, films have been found to cause the quantumefficiency of photoluminescence to begin to decrease at incidentintensities above 10¹⁴ photons/cm². (D. Y. Zang et al., Appl. Phys.Lett. 60 (2), 189, 1992.)

SUMMARY OF THE INVENTION

The present invention is directed to a small molecule, organic thin filmlaser with very low threshold lasing. Both optically and electricallypumped embodiments are disclosed.

In contrast to spun-on polymeric materials, vacuum-deposition of smallmolecular weight organic materials offers the advantages of excellentthickness uniformity, extremely high materials purity, and ease ofintegration with other conventional semiconductor fabrication processes.

In an exemplary embodiment of the present invention, very low threshold,optically-pumped lasing is achieved in a vacuum-deposited, organic thinfilm comprising a layer of tris(8-hydroxyquinoline) aluminum (Alq₃)doped with DCM laser dyes. A very low lasing threshold is achieved at apump energy density of 1.5 μJ/cm² with a 500 psec excitation pulse.Above the threshold, several extremely narrow (i.e., less than 1 ÅFWHM), linearly polarized Fabry-Perot modes appear in the outputspectrum. The peak output power above the threshold exceeds 30 W from a3×10⁻⁷ cm² output facet, corresponding to a peak power of approximately10⁸ W/cm².

Bright red laser emission is clearly visible from the edge of thedevice. The output laser beam includes several transverse modes whichdiverge in a direction orthogonal to the surface of the device of thepresent invention. The emission is strongly linearly polarized, as onewould expect for laser emission. No appreciable degradation of lasermaterial occurs after several hours of pulsed operation in a drynitrogen atmosphere.

The present invention provides a laser device with a small-molecule,vacuum-depositable organic thin film which exhibits a low lasingthreshold (1.5 μJ/cm²), high efficiency, narrow linewidth (less than 1Å) and high peak power (30 W). The pump threshold corresponds to acurrent density of 10-50 A/cm² for an electrically pumped laser usingsuch materials.

The ease of processing, low threshold and other characteristics ofvacuum-deposited materials opens the door to an entirely new generationof optically and electrically-pumped solid-state lasers usingvacuum-deposited organic semiconductors.

The laser of the present invention can be used in a wide variety ofapplications, including telecommunications, printing, opticaldownconversion, semiconductor circuit etching, thermal processing (e.g.,marking, soldering and welding), spectroscopy, vehicular control andnavigation, measurement devices, optical memory devices, displays,scanners, pointers, games and entertainment systems and sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an arrangement including a laser device in accordance withthe present invention.

FIG. 2 shows the spectrum of the edge emission from a device inaccordance with the present invention.

FIGS. 3 and 3A show spectra of the edge emission from a device inaccordance with the present invention at different excitation levelsnear the lasing threshold.

FIG. 4 shows, for a device in accordance with the present invention, thedependence of the output emission intensity on the input pump energydensity near the lasing threshold of the device.

FIG. 5 shows the polarization of the emission of a device in accordancewith the present invention, as a function of the angle between a planeorthogonal to the film surface and the plane of a polarizer.

FIGS. 6A and 6B show further embodiments of optically-pumped laserdevices in accordance with the present invention.

FIGS. 7A and 7B show embodiments of electrically-pumped laser devices inaccordance with the present invention.

DETAILED DESCRIPTION

FIG. 1 shows an optically-pumped laser arrangement including an organicfilm laser 10 in accordance with the present invention. The device ofFIG. 1 comprises a small molecule vacuum-depositable, organic film 12including a layer of tris-(8-hydroxyquinoline) aluminum (Alq₃) dopedwith DCM laser dye. Such a dye is available from Exciton Inc. of Dayton,Ohio.

The device 10 of FIG. 1 exhibits a very low lasing threshold at a pumpenergy density of 1.5 μJ/cm² with a 500 psec excitation pulse. Above thelasing threshold, several extremely narrow, i.e., less than 1 Å FWHM,linearly polarized Fabry-Perot modes appear in the output spectrumbetween 660 nm and 670 nm. The peak output power above the threshold isat, least 30 W from a 3×10⁻⁷ cm² output facet.

Doping Alq₃ with a red dye such as DCM provides an excellent lasermaterial because the red emission (and optical gain) generated is faraway from the absorption edge of the Alq₃ host material (at 450 nm).Doping also allows reduction at the density of the optically active DCMmolecules (thereby reducing the effective density of states), whichlower the threshold and increases the efficiency of the laser.

The concentration of the dopant in the thin film 12 can typically beselected to be less than 10%, by mass, but can be as low as 0.01%. Theoptimal concentration of DCM, i.e., that concentration which will yieldthe lowest lasing threshold, is that concentration which will providesufficient optical gain to overcome the optical losses of the device 10.A low concentration, however, prevents clustering, thereby reducingnon-radiative losses. In an exemplary embodiment, a concentration of1.5% was found to be optimal for a 3 mm long device.

DCM is a good active dopant because it can be vacuum deposited alongwith the Alq₃ and because it has a very high absorbance in the greenspectral range, thereby providing for efficient energy transfer from theAlq₃ to the DCM molecules Other combinations of host and dopantmaterials can be used to form the film 12. For example, ALX can be usedinstead of Alq₃ as the host material and coumarin (C6) can be usedinstead of DCM as the dopant. Any combination of host and dopantmaterials which-allows for good energy transfer between the host anddopant and in which the host is transparent, or nearly transparent, inthe spectral range of the dopant can be used in the optically-pumpedembodiment of the present invention.

Although the laser device 10 described thus far is an optically-pumpeddevice, the Alq₃ /DCM film 12 used in the device 10 has the advantage ofbeing conducive to electrical pumping because Alq₃ is an efficientelectron transporting material.

The laser device of the present invention can be grown on any substrateto which the organic film will adhere and which has a lower index ofrefraction (n) than the organic film material. Acceptable substratesinclude some plastics, glass and silicon coated with SiO₂.

In an exemplary embodiment, the device 10 is grown on a substrate suchas a glass slide 11 by high vacuum (5×10⁻⁷ Torr) co-evaporation of Alq₃and DCM in a molecular ratio of approximately 50:1. This ratio iscontrolled by independently varying the evaporation rate of eachconstituent molecule. A 3000 Å thick film of Alq₃ /DCM, having anoptical index of refraction (n) of 1.7, forms a slab optical waveguidewith glass (n=1.4) as a cladding layer on one side, and air (n=1) on theother. This slab optical waveguide in conjunction with reflective facets12a and 12b of the deposited organic film layer 12 form an opticalresonator. Lateral confinement of the optical mode is achieved bygain-guiding induced by the optical pump beam. The thickness of theorganic film is selected to be large enough to provide waveguidingwithin the organic film. Also, whereas a thickness of 3000 Å is optimalfor single-mode propagation within the Alq₃ /DCM film, higher-ordermodes can be supported by correspondingly thicker films.

The formation of optically smooth, sharp facets 12a and 12b at opposingedges of the device 10 is a natural advantage of vacuum-deposited films.The shape of the facets 12a and 12b will follow the shape of thecorresponding facets of the underlying substrate 11. As such, it isimportant that the facets of the substrate 11 be smooth and parallel toeach other. The above-described process provides a technique forfabricating optical cavities without additional processing. By suchmeans, facet reflectivities of 7% are obtained, which is sufficient toprovide the necessary optical feedback. Furthermore, as is known,optical feedback can be achieved with other structures as well, such asby an optical grating placed underneath the optically pumped region ofthe organic film, thereby forming a distributed feedback structure, ifthe grating blaze separation is mλ/2nc, where m=1, 2, . . .

In the alternative, the film 12 can be deposited :)n the substrate 11and the combination then cleaved to form smooth, sharp facets.

The device 10 of the present invention can be optically pumped using anylight source emitting light of sufficient intensity which can beabsorbed by the host material molecular species. In the exemplaryembodiment of FIG. 1, the device 10 is optically pumped using a nitrogenlaser 21 which generates 500 psec pulses with a wavelength of 337 nm ata 50 Hz repetition rate. As shown in FIG. 1, the pump beam is focused,such as by a cylindrical lens 22, into a 100 μm wide stripe 23 on thefilm surface oriented orthogonal to the facets 12a and 12b of thedevice. The refractive index of the illuminated portion of the organicfilm 12 is higher than that of the non-illuminated portion, therebyproviding confinement of the optical mode in the vertical direction.This is the gain-guiding effect referred to above.

A laser beam 24 is emitted from a facet 12a and/or 12b of the device 10.A typical length for R device in accordance with the present inventionis 25 mm, although devices of shorter length, e.g., 0.5 mm, can beimplemented.

Although the reflectivity of the edge facets is small, this iscompensated for by the comparatively large cavity length, therebyreducing effective optical losses to approximately 1 cm⁻¹ (neglectingwaveguide losses).

Because the material is essentially transparent to DCM red emission, itis not necessary to pump the whole length of the optical cavity toachieve lasing action. Optical gain in the Alq₃ /DCM film is so highthat lasing can be achieved, for instance, by pumping the film of a 25mm long device over only 1 mm of the device's length. However, pumpingthe device over a larger portion of its length, e.g. 20 mm, allows forlower threshold powers.

The edge emission spectrum of the device of the present invention can beanalyzed by a spectrograph and a CCD camera. FIG. 2 shows the spectrumof the edge emission from a device in accordance with the presentinvention. The spectrum of FIG. 2 was exhibited at a pump energy densityof 15 μJ/cm², which is approximately 10 times the lasing threshold ofthe device.

FIG. 3 shows how the emission spectrum of the device of FIG. 1 varies asthe pump energy density varies near the 1.5 μJ/cm² lasing threshold ofthe device. Below the threshold, the edge emission spectrum is dominatedby a broad peak centered at a wavelength of 620 nm. This peak ischaracteristic of spontaneous emission from DCM. No emission from theAlq₃ is seen under any of the pump intensities, thus indicating completeenergy transfer between the Alq₃ host and the DCM. Laser emissionappears as a sharp peak on the long wavelength side of thephotoluminescence spectrum at pump energy densities as low as 1.5μJ/cm². Edge emission spectra are completely dominated by laser peaks athigh excitation levels (i.e., above 5 μJ/cm², as in the spectrum shownin FIG. 2).

FIG. 3A shows a high resolution edge emission spectrum of the device ofFIG. 1 at a pump level of 1.7 μJ/cm². The spectrum of FIG. 3A reveals aset of longitudinal lasing modes. A mode competition process is clearlyindicated by the irregular spacing of these modes. The spectral width ofthe peaks is limited by the resolution of the spectrograph. (Theseparate longitudinal modes of a 25 mm long optical cavity are expectedto have a wavelength spacing of 0.04 Å, which is well below the 1 Åresolution limit of a typical spectrograph.)

FIG. 4 shows the dependence of the device's peak output power to thepump energy density. From this relationship, the lasing threshold can beclearly discerned. Each line segment in the graph of FIG. 4 is a linearfit to empirically measured points. The slopes of the two line segmentsemphasize a change in differential quantum efficiency, from 0.2%, belowthe lasing threshold, to 10% above the lasing threshold. It is to benoted, however, that measured differential quantum efficienciesrepresent a considerable underestimation since the lasing region in anoptically pumped gain-guided device is only a small fraction of thematerial which is being pumped. Hence, most of the pump power is lost innon-lasing regions. The differential quantum efficiency decreases to 7%at excitation levels above 10 μJ/cm² (not shown), corresponding to peakoutput powers exceeding 4 W.

FIG. 5 shows the intensity of laser emission passing through a polarizeras a function of angle between the plane orthogonal to the film surfaceand the plane of the polarizer. The emission is strongly linearlypolarized, as is expected for laser emission. The degree of polarizationmeasured is 15 dB, although it should be noted that this result islimited by the measurement arrangement. The solid line, which is a fitof the empirically measured points, follows sin² (α), where α is thepolarizer angle.

With the exemplary embodiment of FIG. 1, bright red laser emission isclearly visible from the edge of the device. Diffraction of the outputbeam is faintly observed. The output laser beam includes severaltransverse modes which diverge in the direction orthogonal to the devicesurface. The peak intensity of the red laser emission at the outputfacets is 10⁸ W/cm² (corresponding to a measured peak power exceeding 30W) at a pump level of 200 μJ/cm².

All experiments and empirical measurements described above wereconducted under a dry nitrogen atmosphere. No degradation of the Alq₃/DCM film of the device of the present invention was observed afterseveral hours of operation (which corresponds to at least 10⁶ laserpulses). This indicates that the Alq₃ /DCM thin film enjoys a highdegree of photochemical stability and that it is well suited for use inelectrically pumped organic lasers.

Furthermore, the very low lasing threshold of the device of the presentinvention is also a significant advantage over known devices. Assuming acarrier lifetime of 10 ns for Alq₃ and DCM, a lasing threshold energydensity of 1.5 μJ/cm² implies a 10-50 A/cm² threshold current densityfor pulsed electrical injection, assuming that only 25% of electricallyinjected carriers form singlet excitations. The lasing threshold can bereduced even further by controlling the doping concentration andincreasing the facet reflectivities, both of which are factors affectingthe efficiency of the laser device.

The device of the present invention also overcomes the problems relatedto quenching processes in small-molecule organic materials. Suchquenching processes are observed at high carrier densities and lead todecreased photoluminescence quantum efficiency. It has been found that,due to bimolecular reactions, the quantum efficiency ofphotoluminescence of Alq₃ films begins to decrease at incidentintensities above 10¹⁴ photons/cm². The device of the present invention,however, has a lasing threshold which is at pump intensities of onlyapproximately 10¹² photons/cm², leaving a substantial margin forincreasing pump intensities without encountering a decrease inefficiency due to bimolecular recombination.

FIG. 6A shows a further embodiment of an optically-pumped laser inaccordance with the present invention. In this embodiment, an additionallayer 13 is provided between the substrate 11 and the organic activelayer 12. The layer 13 has an index of refraction lower than that of theorganic layer 12 and serves to increase optical confinement in theactive layer in the direction normal to the surface of the device.

FIG. 6B shows yet another embodiment of an optically-pumped laser inaccordance with the present invention. In this embodiment, the layer 13is deposited on a ridge-patterned substrate. In this case, the layer 13forms a ridge on top of the substrate 11 on which the active organiclayer 12 is deposited. In this embodiment, the optical mode is confinedin both the z-direction as well as in the y-direction. The width of thelayers 12 and 13 should preferably be narrow enough to support only asingle lateral optical mode (e.g., 1-10 μm). The thickness of the activeorganic layer 12 should be approximately equal to the reciprocal of theabsorption coefficient of the host material at the wavelength of thelight with which the device is pumped. If a reflective layer (not shown)is placed between the layer 13 and the substrate 11, the thickness ofthe organic layer 12 should be approximately half the reciprocal of theabsorption coefficient of the host material at the wavelength of thelight with which the device is pumped. To protect the laser device ofFIG. 6B, the device can be overcoated with a transparent material (notshown) whose index of refraction is lower than that of the activeorganic layer 12.

In addition to the optically-pumped embodiments discussed above, thepresent invention also provides an electrically-pumped organicsemiconductor laser.

FIG. 7A shows an embodiment of an electrically-pumped laser device inaccordance with the present invention. A bottom electrode 31, a bottomcladding layer 32, an organic active layer 33, a top cladding layer 34and a top electrode 35 are deposited, in sequence, over a substrate 30.The optical confinement in the active layer 33 depends on the indices ofrefraction of the cladding layers 32 and 34.

As in the case of the optically-pumped laser device, the active layer 33can be composed of Alq₃ /DCM. Either one of the cladding layers iscomposed of a hole conducting material, such as MgF₂ doped with TPD. Toget good hole mobility, a 10% concentration of TPD will suffice. Theother one of the cladding layers is composed of an electron conductingmaterial, such as Alq₃ or MgF₂ doped with Alq₃. For either claddinglayer 32 or 34, the MgF₂ can be replaced with another alkali halide suchas LiF, KF or KI or with a transparent, low index of refraction,conducting organic material. Electrons and holes are injected into theactive layer 33 where the energy is transferred from the conducting hostmaterial to the dopant molecules, which emit light.

An optical resonator is formed by the edges of the film, i.e., mirrorfacets M1 and M2. At least one of the electrodes 31 and 35 is patternedinto a stripe oriented in the x-direction. That portion of the activematerial which is electrically pumped experiences a change in opticalgain, thus forming a waveguide in the lateral direction (i.e., thegain-guiding effect).

In the electrically-pumped laser device of the present invention, theindex of refraction of the active layer 33 must be higher than that ofthe cladding layers 32 and 34. This ensures that most of the modeoverlaps with the gain layer. Preferably, the indices of refraction ofthe cladding layers 32 and 34 should be substantially equal to provideoptimal optical confinement.

The cladding layers 32 and 34 should be thick enough to substantiallyprevent absorption of the optical mode at the electrodes 31 and 35 andto allow for efficient current injection. The thicknesses of thecladding layers can be determined in a known manner. For single-modeoperation, the thickness of the active layer 33 should be substantiallyequal to the lasing wavelength divided by twice the index of refractionof the active layer. For higher modes, the thickness of the active layer33 should be accordingly greater.

Optical confinement can also be achieved by photo-bleaching the activelayer 33 to define a waveguide in the active layer. Using thistechnique, once the active layer 33 has been deposited, a photomask isapplied which partially covers the active layer 33 and the layer isexposed to intense UV light in an O₂ environment. The unmasked portionsof the active layer 33 are thus bleached, lowering their index ofrefraction. The masked portion of the active layer 33 retains itsoriginal, higher index of refraction and is thus optically confined in alateral direction.

Optical confinement can also be achieved by patterning the substrate orbottom cladding layer to achieve index guiding (similar to theoptically-pumped embodiment of FIG. 6B). For example, photo-bleachingcan be used on the bottom cladding layer 32 to create an index modulateddistributed Bragg reflector under the active layer 33.

An optical resonator can also be formed in the z-direction. In thiscase, the top and bottom electrodes also serve as optical mirrors, or,if the electrodes are transparent to light, high reflectivity mirrorscan be added on both sides of the structure. The maximum of the opticalmode of this structure should spatially match the position of theoptical layer. Furthermore, the wavelength of the optical mode shouldoverlap with the gain spectrum of the dopant molecule.

FIG. 7B shows a further embodiment of an electrically-pumped laserdevice in accordance with the present invention. In this embodiment, thebottom electrode 31 extends beyond the laser structure so as to providea contact surface. Additionally, an insulator 37 is provided on a sideof the laser structure and a contact 36 extending from the upperelectrode 35 to the surface of the substrate 30 is deposited on theinsulator.

The present invention was developed with funding provided, in part, bythe Air Force Office of Scientific Research and by the National ScienceFoundation.

The subject invention as disclosed herein may be used in conjunctionwith co-pending applications: "High Reliability, High Efficiency,Integratable Organic Light Emitting Devices and Methods of ProducingSame," Ser. No. 08/774,119 (filed Dec. 23, 1996), for which the IssueFee was paid on Sep. 23, 1999; "Novel Materials for Multicolor LED's,Ser. No. 08/850,264, " Attorney Docket No. 10020/24 (filed May 2, 1997),Ser. No. 08/850,264, for which the Issue Fee was paid on Jan. 21, 2000;"Electron Transporting and Light Emitting Layers Based on Organic FreeRadicals," Ser. No. 08/774,120 (filed Dec. 23, 1996), now U.S. Pat. No.5,822,833; "Multicolor Display Devices,"Ser. No. 08/772,333 (filed Dec.23, 1996), now U.S. Pat. No. 6,013,982; "Red-Emitting Organic LightEmitting Devices (LED's)," Ser. No. 08/774,087 (filed Dec. 23, 1996),for which the Issue Fee was paid on Jul. 21, 1999; "Driving Circuit ForStacked Organic Light Emitting Devices,"Ser. No. 08/792,050 (filed Feb.3, 1997), now U.S. Pat. No. 5,757,139; "High Efficiency Organic LightEmitting Device Structures," Ser. No. 08/772,332 (filed Dec. 23, 1996),now U.S. Pat. No. 5,834,893; "Vacuum Deposited, Non-Polymeric FlexibleOrganic Light Emitting Devices," Ser. No. 08/789,319 (filed Jan. 23,1997), now U.S. Pat. No. 5,844,363; "Displays Having Mesa. PixelConfiguration," Ser. No. 08/794,595 (filed Feb. 3, 1997); "StackedOrganic Light Emitting Devices," Ser. No. 08/792,046 (filed Feb. 3,1997), now U.S. Pat. No. 5,917,280; "High Contrast Transparent OrganicLight Emitting Device Display," Ser. No. 08/821,380 (filed Mar. 20,1997), now U.S. Pat. No. 5,986,401; "Organic Light Emitting DevicesContaining A Metal Complex of 5-Hydroxy-Quinoxaline as A Host Material,Ser. No. 08/838,099" Attorney Docket No. 10020/21 (filed Apr. 14, 1997),Ser. No. 08/838,099, now U.S. Pat. No. 5,861,219 and "Light EmittingDevices Having High Brightness, Ser. No. 08/844,353" Attorney9 DocketNo. 10020/16 (filed Apr. 18, 1997) Ser. No. 08/844,353, which has beenallowed, each co-pending application being incorporated herein byreference in its entirety. The subject invention may also be used inconjunction with the subject matter of each of co-pending U.S. patentapplication Ser. Nos. 08/354,674, now U.S. Pat. No. 5,707,745,08/613,207, now U.S. Pat. No. 5,703,436, 08/632,322 now U.S. Pat. No.5,757,026, and 08/693,359 and provisional patent application Ser. Nos.60/010,013 which was coneverted to a regular application and is now U.S.Pat. No. 5,986,268. 60/024,001 which was converted to a regular U.S.Pat. No. 5,844,363; and 60/025501 which was converted to a regular U.S.application Ser. No. 08/844,353, which has been allowed, each of whichis also incorporated herein by reference in its entirety.

What is claimed is:
 1. A laser comprising:a substrate; and a layer ofthin film organic material arranged on the substrate whereinthe organicmaterial has an index of refraction greater than an index of refractionof the substrate, and the organic material lases when pumped to therebyproduce laser light.
 2. The laser of claim 1, wherein the organicmaterial includes a photoluminescent organic material doped with a laserdye.
 3. The laser of claim 1, wherein the organic material is appliedonto the substrate by vacuum deposition.
 4. The laser of claim 2,wherein the photoluminescent organic material includestris(8-hydroxyquinoline) aluminum (Alq₃).
 5. The laser of claim 2,wherein the laser dye includes DCM.
 6. The laser of claim 1, wherein theorganic material includes a host material doped with a guest material,and wherein an electroluminescent spectrum of the host material and anabsorption spectrum of the guest material overlap.
 7. The laser of claim1, wherein the organic material includes a host material doped with aguest material, and wherein energy absorbed by the host material istransferred to the guest material.
 8. The laser of claim 1, wherein thesubstrate includes glass.
 9. The laser of claim 1, wherein the layer oforganic material includes two reflective facets substantially parallelto each other, thereby forming an optical resonator.
 10. A lasercomprising:a substrate; a first electrode arranged on the substrate; afirst cladding layer arranged on the first electrode; an active organiclayer arranged on the first cladding layer; a second cladding layerarranged on the active organic layer; and a second electrode arranged onthe second cladding layer.
 11. The laser of claim 10, wherein the activeorganic layer includes a photoluminescent organic material doped with alaser dye.
 12. The laser of claim 10, wherein the first cladding layerincludes a hole conducting material and the second cladding layerincludes an electron conducting material.
 13. The laser of claim 10,wherein the first cladding layer includes an electron conductingmaterial and the second cladding layer includes a hole conductingmaterial.
 14. The laser of claim 10, wherein the active organic layerhas an index of refraction greater than an index of refraction of thefirst cladding layer and greater than an index of refraction of thesecond cladding layer.
 15. The laser of claim 14, wherein the activeorganic layer includes a photoluminescent organic material doped with alaser dye.
 16. The laser of claim 15, wherein the photoluminescentorganic material includes tris(8-hydroxyquinoline) aluminum (Alq₃). 17.The laser of claim 15., wherein the laser dye includes DCM.
 18. Thelaser of claim 10, wherein the active organic layer includes a hostmaterial doped with a guest material, and wherein an electroluminescentspectrum of the host material and an absorption spectrum of the guestmaterial overlap.
 19. The laser of claim 10, wherein the active organiclayer includes a host material doped with a guest material, and whereinenergy absorbed by the host material is transferred to the guestmaterial.
 20. The laser of claim 10, wherein the substrate includesglass.
 21. The laser of claim 10, wherein the active organic layerincludes two reflective facets substantially parallel to each other,thereby forming an optical resonator.
 22. The laser of claim 1, whereinthe laser is incorporated into a communications device.
 23. The laser ofclaim 10, wherein the laser is incorporated into a communicationsdevice.
 24. The laser of claim 1, wherein the laser is incorporated intoa printer.
 25. The laser of claim 10, wherein the laser is incorporatedinto a printer.
 26. The laser of claim 1, wherein the laser isincorporated into an etching system.
 27. The laser of claim 10, whereinthe laser is incorporated into an etching system.
 28. The laser of claim1, wherein the laser is incorporated into a measurement device.
 29. Thelaser of claim 10, wherein the laser is incorporated into a measurementdevice.
 30. The laser of claim 1, wherein the laser is incorporated intoan optical memory device.
 31. The laser of claim 10, wherein the laseris incorporated into an optical memory device.
 32. A laser comprising:asubstrate; a layer of thin film organic material arranged on thesubstrate; and a light source for optically pumping said organicmaterial; whereby said organic material lases when pumped with saidlight source.
 33. The laser of claim 32, wherein said organic materialcomprises tris (8-hydroxyquinoline) aluminum (Alq₃).
 34. The laser ofclaim 33, wherein said organic material further comprises a dyecomprising DCM.
 35. The laser of claim 32, wherein said layer of organicmaterial includes two reflective facets substantially parallel to eachother, thereby forming an optical resonator.
 36. The laser of claim 1,wherein the organic material comprises small molecules.
 37. The laser ofclaim 1, wherein the organic material consists essentially of smallmolecules.
 38. The laser of claim 10, wherein the active organic layercomprises small molecules.
 39. The laser of claim 10, wherein the activeorganic layer consists essentially of small molecules.
 40. The laser ofclaim 32, wherein the organic material comprises small molecules. 41.The laser of claim 32, wherein the organic material consists essentiallyof small molecules.
 42. A laser comprisinga substrate; and a layer ofthin film organic material arranged on the substrate, wherein theorganic material has an index of refraction greater than an index ofrefraction of the substrate, and the organic material lases when pumpedto thereby produce laser light; and wherein the layer of organicmaterial includes two reflective facets substantially parallel to eachother, thereby forming an optical resonator.
 43. The laser of claim 42,wherein the organic material includes a photoluminescent organicmaterial doped with a laser dye.
 44. The laser of claim 42, wherein theorganic material is applied onto the substrate by vacuum deposition. 45.The laser of claim 43, wherein said organic material comprisestris(8-hydroxyquinoline) aluminum (Alq₃).
 46. The laser of claim 43,wherein the laser dye includes DCM.
 47. The laser of claim 42, whereinthe organic material includes a host material doped with a guestmaterial, and wherein an electroluminescent spectrum of the hostmaterial and an absorption spectrum of the guest material overlap. 48.The laser of claim 42, wherein the organic material includes a hostmaterial doped with a guest material, and wherein energy absorbed by thehost material is transferred to the guest material.
 49. The laser ofclaim 42, wherein the substrate includes glass.
 50. The laser of claim42, wherein the organic material comprises small molecules.
 51. Thelaser of claim 42, wherein the organic material consists essentially ofsmall molecules.
 52. A laser comprising:a substrate; a first electrodearranged on the substrate; a first cladding layer arranged on the firstelectrode; an active organic layer arranged on the first cladding layer;a second cladding layer arranged on the active organic layer; and asecond electrode arranged on the second cladding layer; wherein theactive organic layer includes two reflective facets substantiallyparallel to each other, thereby forming an optical resonator.
 53. Thelaser of claim 52, wherein the active organic layer includes aphotoluminescent organic material doped with a laser dye.
 54. The laserof claim 52, wherein the first cladding layer includes a hole conductingmaterial and the second cladding layer includes an electron conductingmaterial.
 55. The laser of claim 52, wherein the first cladding layerincludes an electron conducting material and the second cladding layerincludes a hole conducting material.
 56. The laser of claim 52, whereinthe active organic layer has an index or refraction greater than anindex of refraction of the first cladding layer and greater than anindex of refraction of the second cladding layer.
 57. The laser of claim56, wherein the active organic layer includes a photoluminescent organicmaterial doped with a laser dye.
 58. The laser of claim 57, wherein thephotoluminescent organic material includes tris(8-hydroxyquinoline)aluminum (Alq₃).
 59. The laser of claim 57, wherein the laser dyeincludes DCM.
 60. The laser of claim 52, wherein the active organiclayer includes a host material doped with a guest material, and whereinan electroluminescent spectrum of the host material and an absorptionspectrum of the guest material overlap.
 61. The laser of claim 52,wherein the active organic layer includes a host material doped with aguest material, and wherein energy absorbed by the host material istransferred to the guest material.
 62. The laser of claim 52, whereinthe substrate includes glass.
 63. The laser of claim 52, wherein theactive organic layer comprises small molecules.
 64. The laser of claim52, wherein the active organic layer consists essentially of smallmolecules.
 65. The laser of claim 42, wherein the laser is incorporatedinto a communications device.
 66. The laser of claim 52, wherein thelaser is incorporated into a communications device.
 67. The laser ofclaim 42, wherein the laser is incorporated into a printer.
 68. Thelaser of claim 52, wherein the laser is incorporated into a printer. 69.The laser of claim 42, wherein the laser is incorporated into an etchingsystem.
 70. The laser of claim 52, wherein the laser is incorporatedinto an etching system.
 71. The laser of claim 42, wherein the laser isincorporated into a measurement device.
 72. The laser of claim 52,wherein the laser is incorporated into a measurement device.
 73. Thelaser of claim 42, wherein the laser is incorporated into an opticalmemory device.
 74. The laser of claim 52, wherein the laser isincorporated into an optical memory device.
 75. A laser comprising:asubstrate; a layer of thin film organic material arranged on thesubstrate; and a light source for optically pumping said organicmaterial; whereby said organic material lases when pumped with saidlight source; wherein said layer of organic material includes tworeflective facets substantially parallel to each other, thereby formingan optical resonator.
 76. The laser of claim 75, wherein said organicmaterial comprises tris(8-hydroxyquinoline) aluminum (Alq₃).
 77. Thelaser of claim 75, wherein said organic material further comprises a dyecomprising DCM.
 78. The laser of claim 75, wherein the organic materialcomprises small molecules.
 79. The laser of claim 75, wherein theorganic material consists essentially of small molecules.